https://doi.org/10.1351/goldbook.15350
System containing \(n\) ionic species with or without a single solvent. Because of electrical neutrality, the system has \(n\) components in an aqueous system with a single solvent and \(n - 1\) components in a molten salt system.
Notes:
- There is a special notation for reciprocal salt systems that involves use of double vertical bars. All ionic species are specified. For example, \[\ce{K^{+},Na^{+} \Vert\ Cl^{-},NO3^{-} + H2O}\] denotes a four-component (quaternary) aqueous reciprocal salt system in which each cation can combine with each anion to produce anhydrous, hydrated, binary, or ternary solid components; i.e., the solution may become saturated with respect to any one of \(\ce{KCl}\), \(\ce{NaCl}\), \(\ce{KNO3}\), \(\ce{NaNO3}\), their hydrates, or anhydrous or hydrated binary compounds of the simple salts.
- Ternary aqueous systems containing a common ion can be considered as a limiting case of this class of system, where there is only one cation or one anion. For example, \[\ce{Na^{+},Zn^{2+} \Vert\ SO4^{2-} + H2O}\]